The hoistable mast electronic unit (HMEU) controls hoisting, retracting and positioning of masts consisting of one or more telescopic elements on board a submarine. The hydraulic mast operation is accomplished by bi-directional valves, which are controlled by the HMEU. The system is designed for low noise and safe mast control with minimal demands on the hydraulic system.

The HMEU can be operated from multi-function consoles, from the weapon control system by means of software driven user interfaces, or locally at the HMEU itself. The local control features include suppression of any mast movements when berthed in port and disengagement of the speed- and depth-dependant auto retraction.